Predetermined torque release and torque indicating wrench



July 6, 19554 K. R. LARsoN 2,682,796

PREDETERMINED TORQUE RELEASE AND TORQUE INDICATING WRENCH Filed Sept. 23, 1949 3 Sheets-Sheet l July 6, 1954 PREDETERMINED ToEQUE RELEASE AND ToRQuE INDICATING WRENCH Filed sept. 25, 1949 K. R. LA RSON July 6, 1954 K R, LARSON 2,582,796

PEEDETERMINED TORQUE RELEASE AND ToRQuE INDICATING WRENCH Filed sept.4 25, 1949 3 sheets-sheet 3 Patented July 6, 1954 PREDETERMIED TORQUE RELEASE AND TORQUE INDICATING WRENCH Kenneth R. Larson, Des Plaines, Ill., assignor to Snap-0n Tools Corporation, a corporation of Delaware Application September 23, 1.949, Serial No. 117,327

17 Claims. 1

This invention relates to turning devices and more particularly to torque measuring wrenches of the type illustrated in United States Letters Patent No. 2,312,104 issued Februaryy 23, 1943, although certain features thereof maybe employed with equal advantage for other purposes.

It contemplates more especially the provision of a simple, dependable, accurate and compact torque measuring wrench that accurately designates the pre-set force to be applied in nut turning and similar movements under all conditions.

Most torque wrenches measure the flex in a beam which resists the turning force of a wrench in order to measure the amount of torque or force applied in nut turning and similar operations. Then, too, the amount of torque has been measured by determining the degree of twist in a shank or shaft.Y While some torque wrenches have embodied this principle and an appreciable effort recently has been successfully made to adapt such to commercial wrench structures of the conventional handle or lever arm type as evidenced by the aforementioned Letters Patent No. 2,312,104, it is now deemed more effective topre-set a wrench of the type so that the desired nut or other fastener tightening `load will be indicated during use to preclude further tighteningV thereof. The desirability of utilizing the degree of twist in the shank or shaft as the 'measuring expedient in nut turning and similar operations, has been resorted to with success from the standpoint of translating the degree of twist to an indicator ata point of maximum vdisplacement so that accurate measurements can be recorded by reducing the error factor to a minimum as illustrated inthe above referred to Letters Patent; however, it is now known that predetermined tightening loads can vbe imparted to fasteners by incorporating presetting control instrumentalities to preclude variations in fastener turning loads without jarring the sensitive measuring elements thereof.V

' The importance of accuracy in torque wrenches cannot be over-emphasized, and the degree of accuracy depending largely upon the elimination of or substantial reduction in friction, lag and free-play between relatively moving parts. This is also important in torque wrenches that embody the principle Vof flexing a torque resisting beam to provide the desired reading;`how ever, better results have been found possible in torsion type wrenches embodying teachings of the present invention.

In accordance with the teachings of the present invention, the` torsion measuring principle ver-arm wrench with minimum friction,. lag, free-play, and maximum translation of the relative twist of the load carrying member. This has been accomplished in conjunction with presetting torque load indicator instrumentalities which preclude errors and variations in reading and interpreting the usual indicators in all conditions of use. Torque measurements are possible, therefore, with a negligible error factor and nut turning operations are accurately measured under all conditions and capacities irrespective of human error and the position of applied force along the lever-arm for effecting the turning operation.

It has been found in actual use of torque wrenches, that the attendant may not be too observant of the indicator dial or he may be working in such an obscure or inconvenient position for the purpose of nut turning with difculty in normally inaccessible places so that there is little opportunity to read the dial and, therefore, the user `of a torque wrench may not be in the position toV determine with any great deal of accuracy the torque load that is being applied. Furthermore, human error may render otherwise accurate torque measuring instrumentalities ineffectual so that the present invention contemplates the elimination of human error and the other noted difliculties by providing visual as well as physical signals that will convey to the attendant the knowledge that the applied torque has reached the predetermined value at which the measuring instrumentalities have been pre-set prior to the application of the wrench. To this end, it has been found desirable to provide audible, visual and physical indicators so that there would be no possible chance of the attendant to apply more torque load to a fastener than is initially intended.

The physical indicator may take the form of a releasable expedient which will provide a slight impact against the person of the attendant such as his hand which is being used for the application of nut turning force. With such an expedient, it would be impossible yfor the attendant to continue applying a torque load after receiving the physical signal that is controlled by the pre-setting expedients. This would be true irrespective of the position in which the attendant was using the torque wrench or the inacces- Sibility of use which may preclude the direct Vision to the calibrated indicator or measuring meter that has heretofore been used in devices of this character. These human failures have been entirely eliminated by utilizing a combination of indicators that are actuated by the pre-setting instrumentalities when the torque load reaches the measurement for which the wrench is preset.

One objecty of the present inventionisto sim,- plify the constructionand improve thezopera'- tion of devices of the character mentioned.

Another object is to provide a simple and oom-.-`

pact torque measuring Wrench of the lever-arm type that is accurate, dependable-ini-operation;k and embodies presetting control means for accurately indicating the tightening-loads,

Still another object is to .provide-.a torque` measuring turning tool having improved torsion translating means associated therewith in conjunction with presetting indicator instrumentalities which provide visual, physical and audibler signals for indicating the torque applied in the turning operation at apreset value.

A further object is to provide, a torque. measuring turning vtool Withv instrumentalities for operating a trigger release indicator at .any Dre. determined torque load.

A still further object isv to provide a torque Wrench with a turning shank having trigger release -presetting indicator means to control vthe extent toY which anyfastener maybe tightened by giving the attendant a physical impulse.

Still a further object is to provide a. Wrench having a rigid casing element for attachment of a turning shank subjected to turning ,movement to providealcalibratedtorque load conjunction vvith presetting measuring control4 instrumentalities embodying. visual, audible, and physical indicator expedients to limit the fura ther application of force by theattendant.

An additional object is toprovide .animproved preset releasable impacting signal means in torque wrenches to lindicate to rthe attendant that the torque load has reached a preset. value.

Other objects and advantageswillappear from the following description ,of an. illustrative .embodiment oi the present invention.A

In the drawings:

Figure 1 is a plan view of a Wrench embodying features ofthe present invention.

Figure 2 f is va side vievvV lin elevation. of the wrench shown inFigurel.

Figure 3 is a bottom" plan view of the wrench shown in Figure 1.

Figure 4 is a sectional view taken substantially along line IV-IV of Figure 3.

Figure 5 is ia sectional View taken substantially along line -V.-V of Figure 1.

Figure 6 is a sectionalview taken substantially along line VI-VI of Figure 1.

Figure '7 is a-p1an view of an underside -of a casing cover plate and its assembled instrumentalities.

Figure 8 is a sectional view taken substantially along line VIII- VIII of Figure .6..

Figure 9 is a sectional view in elevation taken substantially along line IX-IX of `Figure 6.V

Figurek 10 is a sectional viewin elevationtaken substantially along line X-X vof Figure.

Figure 11 is asectional View taken along line XI-XI of Figure 7.

Figure 12 is a plan View of another embodiment of the present invention.

Figure 13 is a View similar to Figure 12 .with the top casing plate removed to show the casing interior and instrumentalities confined therein.

Figure 14 is a sectional view in elevation; taken substantially along line XV-XIV of Figure 13.

Figure 15 is a sectional View in elevation taken substantially along line XV-XV of Figure 13.

Figure 16 is a sectional view in elevation taken substantially along line XVI-XVI of Figure 13.

Figure 17 is a bottom plan viev/ of the presetting.,calibrated.dial shown assembledin top plan inv Figure 12.

The structure selected'for illustration is not intended to serve as a limitation upon the scope or teachings of the invention, but is merely illustrative-thereoi There may be considerable variations .and adaptations of all or part of the teachings dependingupon. the dictates of commercial practice... 'I'he Ipresent embodiment comprises a 'soli'dhandle'lmember I0 of standard construction having an elongated chambered Wrench shank or bodyf/II cast orlotherwise shaped to present inclinedsside walls I2 and I3 terminating in a semi-circular top or head extremity I-4. The handle I0 with its chambered body II is. preferably though not 'essentiallycastfrom an aluminum1 alloy-so vas to' Ypossess the desired strength and lightness `for -convenience and Vmanipulation inl nut turning as Will appearmore fullyhereinafter. It"will"'be' observed `that the handle shank'V or body II consists 'of "thefinclined side Walls I2-'-I3 which"converge"in thefdirection of the handle III vand also :toward the 'bottom Wall I5 formed "integral therewith todene'anelongated chambered interior IB.` It'sh'ouldbe noted that, in this instanceyth'e sidewalls I2-'I3 not only converge towardthe'handle'l .,(Figures 1 and 9) butA also towardl :theb'ottom VI5` (Figures 3 and 9)v to define acompactand'well balanced casing or body I I Thebody or casing'shank `I I is;in this instance, covered by arigidsteel plate-'I'I'that is .shaped to `conform with' the configuration of the 'peripherally flanged-'open 'side' I8` opposite the 'bottom Wall I 5 to confront'therewithand serve as a vcornplement thereof. The loWerorA handle extremity I 9 of the chamber II!! is of the same Igeneral semicircular configuration'as the head extremity Id. The peripherallyflangedopen'edgeI8"of the casing VII extends around'the'side WallsV I2-I3 and their semi-circular head' and handle 1 extremities I4 'andISk The rigid'face'or cover'plate I'Iis shaped to correspond with the angedopen vedge I8 Lincludingfits `upper.and...lovver semi-circular head and handle' extremities I4 "and I9 to serve as an enclosure thereforandarigid turning'arm to Which the measuring l instrumentalities are attached as well appear. more fully hereinafter.

A -plurality of threaded screw/'fasteners 2Il'project through apertures 2 I. in the rigid cover plate I'I Vto engage correspondinglythreadedbores 22 inI theperipheral casing4 edge` I8 Ythat extends along the side Walls I2--I 3 of the handle shank or casingbody' II and. -semi-circularends Il--I9, therebyenclosing the'chamber IS and confining the torsion'displacing;indicating, and measuring instrumentalities to `be 'described hereinafter. It will be noted'v that the'handle shank or casing body II and especially the inclined side walls I2-.i-I3. areY reinforced inv the` region' of the threaded .bores 22 by increasing the thickness of the rcase peripheral flange I 8 as at 23-2,2526, and ZT-ZS so that the .comparatively rigid and load. carryingy cover plate I1 .can be effectively attached to the casing body II which is greatly strengthened and reinforced therewith.A

In fact, the casing- I I does not sustain any appreciable turning. load and primarily` serves to confine the measuring.instrumentalities as aprotection against 'foreign substances and impacts.

The cover plate I1 is sufficiently rigid to avoid a ex, distortion or consequential variation under turning load. The semi-circular head I4 of the body II is provided with a circular recess 2B corresponding substantially in curvature therewith and sized to receive a revoluble turning member of substantially corresponding size for free rotation therein. The revoluble turning member 30 has an annular shoulder 3I formed, in this instance, integral therewith immediately above a polygonal wrench socket receiving extremity 32 which terminates beyond the bottom I5 of the casing shank II for projecting through the circular recess 29 provided in the head I 4. A spring impelled detent 33 of standard construction is provided in a face of the polygonal shank 32 for cooperation with a correspondingly sized and shaped recess provided in a wrench socket or other turning implement that is telescoped thereon for retention thereon against accidental detachment.

Wrench sockets or other turning implements (not shown) would normally be provided with a recessed shank shaped and sized to conform with the polygonal extremity 32 of the revoluble turning member 30 so that the friction exerted by 'the spring impelled detent 33 would be effective lation therewith. The cylindrical turning shank 34 terminates in an enlarged polygonal flange 35 having, in this instance, a circular configuration which may be of any polygonal shape depending upon the dictates of commercial practice. So that the revoluble turning member 3D may be atf tached to the cover plate I1 to constitute a fixed element thereof, the cover plate I1 and the flange of the revoluble turning member 30 are welded together in a manner known in the art to anchor the turning member 3D rigidly thereto against any relative movement at their juncture.

It should be noted that the revoluble turning member 30 is rigidly attached to the cover plate I1 that is preferably of rigid and non-yielding material such as steel while the body or casing shank II may be cast or otherwise shaped from aluminum in 'that the revoluble turning member 30 is mounted for movement relative thereto in sustaining the turning load. The casing I I does not directly carry any appreciable load. Turning movement is imparted to a fastener such as a threaded nut through a wrench socket attached to the polygonal shank 32 of the revoluble turning member 30, responsive to manually applying force or effort to the handle I0 in one direction or another.

In order to measure the extent to which any fastener such as a threaded nut is appliedthrough the manipulation of the handle I0, the extent of twist sustained by the cylindrical extension 34 of the revoluble turning member 30 is determined in that this will be uniform for any predetermined applied force and will Vary proportionately to the turning load imparted through the handle I0 that is primarily sustained by the rigid cover plate I1. It will be observed that owing to the rigid anchored attachment of the turning shank 30 to the cover plate I1 through the medium of the iiange 35, any turning movement appliedto the handle I0 will be transferred to the cover plate I1 which, in turn, will rotarily displace the turning shank member 30'which carries a nut or other turning implement to the end that proportional twist is imparted to the cylindrical extension 34 anchored to the cover plate I1 at one extremity 35 and free to twist at the other extremity 32 responsive to carrying the turning load.

In order to measure the degree of twist or torsion imparted to the cylindrical extension 34 of the revoluble member 30 responsive to any turning displacement or operation, an elongated tapered indicator displacing rod l36, is in this instance of rectangular cross-section, and projects radially in the annular shoulder 3| of the revoluble member 30 as at 31 for fixed engagement to constitute a single acting unit or member therewith. The elongated rod 36 projects longitudinally of the body or casing shank I I lfor confinement therein. So that the casing shank II together with its associated instrumentalities may be as compact as possible, the indicator displacing rod 36 is preferably disposed parallel to the casing bottom I 5 (Figure 6) to avoid contact with either the bottom I5 or cover plate I1 and be completely free to circumferentially move or oscillate for a limited extent depending upon the degree of twist imparted to the revoluble member extension 34 or the tortion effect therein responsive to carrying the turning load imparted to the fastener that is engaged through an appropriate adapter detachably associated with the shank 32.

Ihe elongated indicator displacing rod 36 need only be heavy enough to overcome the friction in the measuring instrumentalities and the load occasioned by their operation Without causing any flex in the rod 36. Its cross-sectional size, however, may be determined by other factors such as the elimination of backlash and conditions of abuse in actual nut turning operations. For that reason,Y the elongated rod 36 in actual practice may be appreciably heavier than otherwise required merely to carry a comparatively negligible load of operating the measuring instrumentalities without any fiex in the rod 36 which is merely a translating medium as will appear more fully from a description of the calibrated indicator instrumentalities. p

It may be more desirable from a manufacturing standpoint to terminate the elongated rod 3S short of the lower handle end I9 of the casing II or cover plate I1 and join therewith a rod extension 31 of comparatively smaller diameter. To this end, the rod extension 31 has its upper extremity 38 projecting within an axial bore 39 provided in the lower extremity of the rod 36. The upper extremity 31 of the rod extension 38 is frictionally engaged by press-fitting or otherwise attached in the bore 39 by any suitable means as commercial practice may dictate to effect rigid connection of the Vrod extension 31 with the elon- `gated actuating rod 3b for cooperation with the measuring instrumentalities (Figures 6 to 9). The lower region of the rod extension 31 is milled `or otherwise shaped to provide a flat side 46 and what more expensive from a production standpoint than the co-axial connected rods 36--31 serving as an actuator for measuring instrumentalities when displaced by the twist imparted to the turning member shank 34. The reduced rod extension 31 projects longitudinally within the casing body chamber I6 near the bottom end I9 thereof for cooperation with improved measuring and indicating instrumentalities to be presently described.

The measuring and indicating instrumentalities comprise, in this instance, pre-set control means for enabling a nut or other fastener to be turned tight to a predetermined torque which is usually\ measured in foot-pounds, although in smaller capacities the measurement may be in inch-pounds. Whatever the scale, however, a trigger mechanism is provided to be released upon turning a nut or other fastener with a predetermined torque load at which time there is a change in the position of the indicator. The degree of twist in the revoluble member shank 34 will serve to displace the rod extension 31 for a proportional extent, and it is this arcuate displacement at a given point which is, in effect, measured. To this end, the flat precision edge 4I of the rod extension 3'! confronts a trigger 42 comprising an elongated rectangular member that depends in confronting relation with the flat edge 4I of the rod extension 31. The trigger 42 is pivoted as at 43 to a block 44. The block 44 is fixed to a comparatively thin plate 45 that is pivoted as at 46 proximate to one extremity 41 thereof, to the underside of the cover plate I1 (Figures 6 and 1).

As shown, the trigger 42 has a protruding shoulder 48 which is pivotally movable therewith within a slot 49 provided in the block 44 to present the shoulder 48 in the path of a rod or plunger 50. The rod or plunger 56 is reciprocally mounted in an upraised boss I extending from the block 44. The upraised boss 5I projects through a laterally extending slot 52 provided in the cover plate I1 to permit restricted lateral displacement thereof along with the plate to which it is attached. As shown, the reciprocable rod or plunger 55 terminates in a flat head 53 (Figures 9 and ll) to confront the flat side 45 of the rod extension 31. In order to normally urge the rod or plunger 50 in an outwardly direction relative to the cover plate I1, a spring 54 is provided in y enveloping relation therewith for confinement in an axial bore provided in the upraised boss 5I of the block 44. A stop in the form of a threaded disc member 55 adjustably engages the threaded projecting extremity 51 of the plunger 55 in order to confine the spring 54 within the bore 55 and to normally urge the plunger 50 outwardly with its lower fiat head 53 projecting against the trigger shoulder 48.

A flat spring 58, in this instance of substantially U-shaped configuration, is fixed to the block 44 by means of fasteners 59-50 to confront the trigger 42 and normally urge the shoulder 48 in the path of the plunger head 53 to engage therewith and retain the plunger 50 inwardly to its extreme position of displacement against the urge of the spring 54. In this position, the plunger head 53 will ride along the incline edge Si of the trigger shoulder 48 and engage therebeneath for retention in this extreme position. A threaded nut or other suitable fastener 62 engages the correspondingly threaded cylindrical extension 53 of the upraised boss 5I to enable the latter to be retained against lateral displacement in any position within the limits of the slot 52.

This will preclude the oscillatable shifting of the block mounting plate 45 relative to its pivot 46.

`This is desirable whenever the pre-setting mechanism is at a predetermined torque load value at which there is to be a repeated number of fastener tightening operations. This is effective in production operations Where an attendant is performing the same operation on different devices for any given period. Now, then, the position of theplate 45 With respect to the pre-setting control instrumentalities, will determine the torque load at which the plunger 50 will be released by reason of the rod extension 31 abutting against the trigger 42 to displace the shoulder 46 from the path of the plunger head 53. To this end, the pre-setting mechanism comprises a calibrated dial 54 which is fixed to a iinger manipulating knob that adjustably engages a stud shaft 5S (Figures 1 and 6). The dial 54 with its knob 55 is fixed to the stud shaft 66 exteriorally of the cover plate I1. The inner end of the stud shaft 55 has a cam 61 ilxed thereto which is rotatable with the dial 64 in the path of a straight shoulder 58 formed on an extension 'te of the plate 45.

The cam 61 has a progressive edge that shifts the plate extension 69 laterally relative to its pivot :i5 for distances commensurate with the torque load calibrations provided on the dial 64 so that a corresponding turning load will impart a twist to the load carrying shank 34 that in turn will translate the rod 5E with its extension 31 in the direction of the trigger 42 to effect the release of the plunger 5t and thus visually indicate to the attendant that the pre-set load for which the dial 54 has been rotatably adjusted, has been reached. Thereupon, the attendant will manually release the force with which the handle I0 is being displaced for accomplishing the fastener tightening operation. As shown, a stop in the form of a pin 15 protrudes inwardly from the cover plate I1 to enable the cam E1 to be turned to its maximum extent in a counter-clockwise direction (viewed from Figure '7) so that it will be impossible to turn the dial B4 in only a single direction for effecting the pre-setting thereof. rlhereupon, the dial 64 through its knob 55 will have to be reversed rather than permit the complete rotation thereof to arrive at the desired presetting position or positions.

In order to maintain the shoulder 58 on the plate extension 69 in constant contact with the cam 51, a coil spring 1I is anchored as at 12 to the extremity 13 of the plate extension 69 while the other end thereof is anchored as at 14 to the underside of the cover plate I1. This precludes any free movement of the pre-setting mechanism and Will insure the displacement of the plate extension `5.13 with its trigger mechanism 42 to correspond with the calibrated indications in footpounds or inch-pounds on the dial 54.

It will be apparent, therefore, that in the event the attendant is called upon to tighten a fastener to a load value within the calibrations provided on the dial 54, the latter is rotated so that the selected torque load on the dial 64 corresponds and aligns with a suitable orienting line such as the arrow 15 which would be impressed or inscribed on the cover plate I1 in confronting relation with the dial G4 disposed thereon. When this load value is imparted to a fastener such as a nut, the plunger 50 which was initially depressed would become released and indicate to the attendant that he is to stop applying any 9 furtherV force,Y release the force that has been applied, and then remove the turning tool from the fastener. If the attendant is engaged in tightening fasteners calling for the same torque turning loads for any given period, the threaded knob 62 is tightened to preclude any-accidental displacement of the dial 64. This will insure the same reading at which the trigger 42 will release the plunger 58 and notify the attendant that the desired torque turning load has been reached.

In 'order to further insure that the attendant will be notified of the release of the plunger 50 under all conditions of illumination and even though the attendant may be working in a very restricted or uncomfortable position, an audible or visual signal can also be provided to operate in conjunction with the trigger 42 and the plunger 50 released thereby. In the present embodiment, a visual indicator has been provided in the form of an electric bulb 16 that is threaded into a socket 'l1 carried by an elongated casing 18 which preferably is fixed to the exterior of the cover plate Il by any suitable means such as the threaded fasteners 'wf-80. A battery 8| is confined in the casing 18 to energize the bulb 16 whenever the plunger 50 has been released. A transparent lens 82 nts over the end of the battery casing 18 to permit the light rays to emanate from the bulb 16.

As shown, the battery casing 18 is preferably of metal such as aluminum which is grounded by contact with the cover plate Il. This grounds onepole of the battery 8l while the other pole thereof is operatively connected to a plunger stop pin 83 (Figure 9) that is insulated in the trigger body or block 44. To this end, the stop pin 83 is carried in an insulator bushing 64 that projects through one side of the trigger body or block 44 to support the inward extremityof the pin 83 in the path of the plunger head 53. A wire 85 connects the insulated bulb socket 1l with the insulated pin 83 to complete the circuit to the battery 8l Whenever the plunger head 53 is released to strike the pin 83 serving as a stop therefor.

Consequently, whenever the plunger 50 is released by the trigger 42, the bulb 16 will be energizedtoprovide a visual signal in conjunction with the released positionl of the-plunger50. It should be noted, also, that the release of the plunger 50 provides an audible click by reason of the impact of the plunger head 53 against the extremity of the pins or stop 83'so that the use of the visual indicator bulb 16 is not absolutel'i7 essential. The visual illuminator 16 is optional and would prove effective only as an additional precaution against the inadvertance that may be indulged in by users or Whenever they -are utiliz'- ing the torque wrench in restricted situations Where full observation is not always possible.

It will be apparent from the foregoing arrangement of parts that a manual turning force applied to the handle I will impart a corresponding turning effect to the revoluble turning member 36. This creates a slight twist in the turning member extension or shank 34 which can be measured with the advantage procured through the moment arm displacing member 36 therebetween. This turning operation is transmitted to a suitable fastener or tool or implement or fastener such as a threaded nut which requires a predetermined turning load in securing it to the devsired degree of tightness for the suitable performance of its intended function.

This turning movement and sustained turning load will create a fractional twist in the revoluble member shank or extension 34 between its annular shoulder 3l and the stationary iiange 35. This fractional twist created by the torsional effect on the cylindrical extension 34, will be translated to the measuring instrumentalities culminating in the arcuate displacement of the rod extension 31 relative to the setting of the trigger 42 through the presetting of the calibrated dial 64 relative to the elongated rod 3'6-37. The degree of twist or torsional strain within the turning member shank 34 is measured at the extreme end of the elongated rod 36-3! which is the point of its greatest displacement relative to the trigger 42 which releases the plunger rod 58 and illuminates the visual signal 16.

As a result, the rod 36-3'1 will accentuate the twist created in the revoluble'head extension 34 to translate this twist arcuately to an extent proportional to the length of the elongated rod 36-3'L The measurement of the twist imparted to the revoluble head extension 34 at a point of maximum displacement of the comparatively l long twist-translating rod 36-31 is an important factor in producing accurate release of the trigger 42.Y Then, too, the rod 36-31 need only :be heavy enough to overcome the comparatively negligible force required to actuate or release the measuring instrumentalities so that comparatively little friction is encountered between the revoluble turning member 36 and the measuring instrumentalities. This isV `conducive to accuracy accomplished with utmost simplicity in construction and operation.

The presetting of the calibrated dial 64 and the release of the plunger 50V with or without the visual indicator 16, precludes errors in reading the usual dials during turning operation thereof and affords an effective and definite stop at which the attendant must release the force of turning as there are no further determinations possible until the next turning operation is encountered and the plunger 55 is depressed to its initial operative position. If a different turning load is required for the next operation, the dial 64 is again preset relative to the arrow T5, and the operation is repeated. This enables resetting of the dial indicator 64 relative to the pointer l5 prior to applying a wrench to an instrumentality that is to be turned therewith. Any abrupt release ofA the nut turning load or the actuation of the trigger 42 to release the plunger 5E), will not shock the sensitive measuring instrumentalities as in the case of directly connected indicating meters such as used in conjunction with known torque wrenches. While there are different forms of automatic release mechanisms on some types of known torque wrenches, these jar the sensitive instrumentalities, create abnormal wear and back lash, and have not proven entirely satisfactory.

With the teachings of the present invention, there is no automatic or sudden release of any load sustaining instrumentality and vonly the indicator is vactuated at the moment the turning load reaches the preset value. The wrench is then gradually and manually released from its turning load. Then, too, the torsional displacement in a torsion-type wrench embodying a comparatively short load turning shank 34 is comparatively small in that the degree of twist therein would be a minute amount approximating five thousandths of an inch under normal loads. Because the elongated rod 36-31 does not actually displace any sensitive dial mechanism at its free end or point of maximum displacement, kthis minute torsional displacement of the load carrying shank 34 is appreciably translated and accentuated at the trigger releasing end of the actuator rod @l-31. Even though there was an abrupt release of load, therefore, the backlash in the aforesaid structure would fbe negligible and the actuator rodea-31 would not be called upon to withstand any appreciable backlash shock which would not, however, be absorbed by any sensitive dial indicator mechanism as none is actually connected therewith.

4In the modified embodiment shown in Figures 12 to 17 inclusive, lthe structure is simplified and further improved by. providing a physicalindicator by placing the trigger release ina position where it will impact against the nger or thumb of the hand that is applied to the handle during the turning movements of the Wrench. This entails the same handle member lll which, in this instance, is slightly offset from the elongated chambered wrench shank or body Il to present an end wall I5 proximate to the handle l0 at its line of integral joinder with the casing Il'. -With this arrangement, e the revoluble turning member Sil is joined with an elongated indicator displacing rod 36 that is slightly offset toward the cover plate Il to provide a free terminal portion 31' that is of somewhat reduced width to confront a trigger 42.

The trigger 42' is pivoted as at 43 to a block 44. The block 44 is fixed to a comparatively .thin plate 45` that is pivoted as at 4S proximate to one end 4l thereof which is nearest the handle l. The comparatively thin plate 45 is pivoted as'at 46 to the `underside vof the cover plate Il (see Figure 14). The trigger 42 has a protruding shoulder 48 which is pivotally movable therewith within a slot` 49' -provided in the block 44 to present the shoulder` 48 in the path of a rod or plunger 50'. The rod or plunger 50' is reciprocally mounted in a bore I provided longitudinally through the block 44 (Figure 13) for communication ,with recessed openings 52- 53 provided in the ends of the-block 44. The endbloek Vrecess 52' communicates with the slot 49 so that the trigger shoulder 48 will be disposable adjacent and in contact Iwith `the rod or plunger 50.

As shown, the rod or plunger 5Uhas enlarged heads 43-55' at both ends thereof with the latter extending through an opening 56 provided in the bottom end I5I of the casing Il adjacent to the,position'that would be occupied by the fingers of the attendants hand which grasp the handle l0. A compressible coil spring 51 Ienvelops the rod or plunger BIV-between the block recess 5l and the lower enlarged head-55 of the rod -orplunger 50 to normally urge the latter outwardly or downwardly in the direction of the handle Ill` unless retained in a preset downwardly displaced position against the urge of the spring 51 by the shoulder 48 of the trigger 42. In this position, the trigger shoulder 48' engages beneath the enlarged inwardhead 54 of the rod or plunger 5B toretain the latter in its preset or cocked position against the urge of the spring 51 and with the other enlarged head 55 thereof out of contact with any portion of the attendants hand which grasps the handle I0.

A iiat spring is xed to the block 44 by means of suitable fasteners 59 to confront the trigger 42 and normallyurge the shoulder 48 thereof in the path of the plunger-head 511 to engage thereunder as itV is manually 'displaced therebeyond in the presetting operation and thus retairrthel plunger inwardly to its extreme position of 'displacementagainst the ,urge of the spring''l. `In this position, theA curved outward surfaceof the plunger head 54 will ride over the trigger` shoulderwV andthe latter willengage therebeneath'ofor retention in' this extreme position. The release of the plunger s effected by ,displacement ofjthe actuating rod'36 against they triggerllZ. So that .there may be some adjustment to properly calibrate the wrench at the factory prior to its delivery the reduced end'3'l of the elongatedactuating rod-,36' abuts against an. arcuate Adetent 60 that is partof a furcated bracketl' vwhich extends over the endof" the triggerv 42'.

The end region ofthe trigger-42 is provided with a plurality of teeth or serrations 62' which mesh with the extremities ofthe arcuatefdetent 60', for retention in any position alongthe limits of the trigger teeth62. A spring 63 engages beneath a pin54" that straddles the Vfurcations of A thebra-clretsl to normallyurge the extremities ofthe arcuatedetent 60' in'meshing engagement with the, trigger teeth 62. Consequently, the furcated bracketi I can be depressed against the trigger', to disengage the arcuate detent Dfrom the trigger teeth `62 and thus permit `the displacement of thedetent 60 along the trigger A2 for the extent of the trigger teeth"62. This will provide` for the `desired adjustment-atf-the factory inorder to calibrate the instrument to accurately correspond withtorque load-calibrations 65 in inch pounds, foot pounds or any other standard of measurement provided on a circular dial 6B', which ,is positioned on the outside of the cover plate l1.

"The ,calibrated kdial B6 is mounted on a stud shaft'l exteriorly ofv the cover plate l1 lwith the -inner `end thereof projecting through' the coveri plate- 11 to terminate within the casing Il. The "inner end ofthe dial mounting shaft 6l has a cam 68 fixed thereto for rotation with the dial-65 in the path of ,a straight shoulder sur-face" -69 formed on an-extension" 70 Aof the pivoted plate 45 to which the trigger mounting block M is attached for oscillatablemovement therewith. The-camv8 has a progressive-edge that shifts the plateextension 10 laterally` relative toits pivot 45 for distances-comensurate with-'the torque load calibrations S5 provided onethe di'al.

Consequently,` a corresponding turning load 1willimparta twist to the-load carrying shank 34 that, ini turn will translate the rod 36 with its .lowergextremityY-.BT' in the'direction of the trigger: 112V to x effect the release of the plunger 50 to thus visually-,and physically,indicate by impact against Athe attendants hand that-a preset load Vfor ywhich the ;dial (56'` has been preset, has

been reached. Thereupon, the attendant .will .manually release the force with which thehandle l0 is -being displaced for accomplishing vthe nut ,orother fastener tighteningy operation. It should .be-observed that `the position of the plate d5 with respectto .the presetting control instrumentali- .tie s, willfdetermine the torque load at which the ,plunger 501will be released by reason of the rod `extremityl abutting against thertriggeri to `displace ,-itsshoulder 48 from thel path of Avthe plunger head` 54.

To the end of ymaintaining the calibrated dial ,66' in lits presetpositionagainstany possible accidental-displacement duringuse of` the wrench,

the underside of thelial-v -isprovidedwitha plurality of circumferentially spaced recesses ll asse-,79e

(Figure 17) which correspond to the calibrations 65 on the exterior surface thereof to cooperate with a spring impelled ball detent l2 mounted in the cover plate I1 (Figure 14). The spring impelled ball detent 12' will be urged in the path of the circumferentially spaced recesses 'H' in the underside of the dial 66 to thus retain the preset position thereof. It will be observed, therefore, that the plunger release 5tL will not only provide a physical signal to the attendant by impact against his hand, but the abrupt release will provide a click that serves as an audible signal as well.

The position of the released plunger 5B also serves as a visual indicator which in conjunction with lan energized light attachment T8 as shown in the preceding embodiment in Figures 1, 2 and 6, there are indicators provided that respond to three human senses, namely visual, audible, and physical to preclude the attendant overlooking and ceasing to apply further force after the preset torque load has been reached. To insureY that the attendant will hold the handle I0 in a position where it will be impacted by the release of the plunger 50 and its head 55', a nger'e'ngaging protrusion 13 is provided on the handle l0 so that the attendant will always grasp the latter with his nger abutting against the handle protrusion 'i3'. It should be understood that the electric light indicator 18 shown in the preceding embodiment may be attached with equal facility to the embodiment shown in Figures'l2 to 17 inclusive and exactly as set forth and described in connection with the embodiments sho-wn in Figures 1, 2 and l6.

With the arrangement of parts above described, it will be apparent that a very simple, inexpensive and highly accurate torque measuring wrench has been provided wherein there are few moving parts and mechanical friction has been reduced to a minimum to preclude variable and inaccurate readings. These features coupled with the fact that the torsional stress created bythe turning load is measured at the point of maximum 'displacement of the elongated dial mechanism actuator rod',fe1iminates or reduces to a negligible minimum any inaccuracies even at small loads. The provision of novel and simple presetting yinstrumentalities' whichset off visual, audible, and physicaly responses the' attendant `at preset torque loads, is a distinct improvement and advance in rendering such devices more readily accurate and to eliminate human error to the maximum. The release of the presetting means rather than directly actuating a calibrated meter,

vaffords greater accuracy and minimum impairmentV to sensitive instrumentalities.

While I have illustrated and described a preferred embodiment of this invention, it must be l understood that the invention is capable of considerable variation and modification without departing from the spirit of the invention. I, theredisplacement in proportion to the torque turning load on said work engaging head member, calibrated means for presetting to a predetermined torque load value, a releasable adjustable indicator for initial positioning to indicate that the torque load is below the preset value and forprcjected positioning upon release when the torque load reaches the preset value, retainer means for holding said indicator in its adjusted position, said retainer means being operatively connected to said calibrated means for positioning responsive thereto in the path of said elongated rod, whereby the displacement of said elongated rodY for contact with said retainer means will release said indicator to its initial unadjusted position when the torque load on said work engaging head member corresponds with the presetting of said calibrated means.

2. In a torque wrench, the combination with an elongated handle member, of a torque responsive work engaging head member operatively associated in torque transmitting relation with one extremity of said handle member, an elongated rod anchored at one extremity to said head member'and extending along said handle member for displacement in proportion to the torque turning load on said work engaging head member, calibrated means for presetting to a predetermined torque load value, a spring actuated releasable adjustable indicator for initial positioning to indicate that the torque load is below the preset value and for projected positioning upon release when the torque load reaches the preset value, spring biased trigger retainer means for holding saidindicator in its adjusted position, said retainer means being operatively connected to said calibrated means for positioning responsive thereto in the path of said elongated rod, whereby the displacement of said elongated lrod for Contact with said retainer means will release said indicator to its initial unadjusted position when the torque load on said work engaging head member corresponds with the presetting of said calibrated means.

3. In a torque wrench, the combination with an elongated handle member, of Va torque responsive work engaging head member operatively associated in torque transmitting relation with one extremity of said handle member, an elongated rod'anchored at one extremity to said head member and extending along said handle member for displacement in proportion to the torque turning load on said work engaging member, calibrated means for presetting to a predetermined torque load value, a plate movably associated with said handle means, cam means interposed between said calibrated means and said movable plate to position the latter responsive to adjusting said calibrated means, a displaceable indicator operatively connected with said shiftable plate for initial positioning to indicate that the torque load is below the preset value and for projected positioning upon release when the torque load reaches the preset value, and retainer means for said displaceable indicator on said movable plate in member and, adapted-to `yield :in responsextoA a torque load thereon, translatable Ameans connected with said Work engaging head member, to move commensurate Withthe yield imparted thereto by the torque load thereon, releasable indicator means disposable in the path of said translatable ymeans forv initial positioning to indicate that rthe torque load is below the preset'valuefand for projected positioning upon release .when :the .torque load reaches the preset value, and cali- .brated torque `'load control means operatively connected with said releasable.indicatorI means to preset the position of the. latter relative to said .translatable-means so that the latter-will operate said releasable indicator meansvvhen said .work` engaging Yhead member is subjected to a torque load for which said. calibrated means has been preset.

5. In a torque IWrench, the combination with a handle. member, of a torquerespcnsive Work engaging head member'operatively connectedin torque transmitting relation with said handle .member and adapted to yield in response to a torque load thereon, translatable means connected with said Work engaging head member to move commensurate with the yield imparted thereto by the torque load thereon, releasable indicator means for initial positioning to indicate that the torque load is below the preset valueand `for projected positioning upon release fwhen the .subjected to a torque load for which said calibrated means has been preset.

6. In a torque Wrench, the combination with a handle member, of a torque responsive work engaging head member operatively connected in torque transmitting relation with said handle member and adaptedto yield in response to a torque load thereon, translatable means connected with said Work engaging head member. to

.move commensurate with the yield imparted vthereto by the torque load thereon, releasable indicator means, retainer trip means cooperable -vvith said releasable indicator means and disposable in the path of said translatable means,

calibrated torque load control means operatively vconnected with said releasable indicator retainer `trip means to preset the position of the latter relative to said translatable means so thatthe latter will operate said releasable indicator `means when said work engaging head member is subjected to a torque load for which said calibrated means has been preset, and spring. means for, normally urging said retainer trip means to normally engage said indicator means in its extreme-position of displacement to indicate that the torque load on said Work engaging Ihead vmemberis not commensuratewith the preset pogsition Iof said calibrated torque vload control zmeans.

'7..In a torque wrench, the combination with a .handle member, of va torque; responsive ,work engaging head member operatively connectedin torque transmitting relation with said handle member and adapted to yield in response to .a .torque load thereon, translatable means con- .nected With said Work engagingv headmember' to y16 movercommensurate .with the .yield imparted thereto` by the torque load thereon,. releasable indicator means, retainer trip meanscooperable with said. releasable .indicator Vmeans and disposable vin the. path of said translatable means, calibrated torque load control means operatively connected with said releasable indicator retainer trip meansto presetlthe position of the latter relative to said translatable means so that the latter will operate said releasable indicator means when said Work engaging head member is subjected` to a torqueload for which said calibrated means has been presetjat spring means for normally urging said retainer trip Vmeansto normally engage .saidindicator means in' its extreme vposition of displacement `to indicate that .the torque loaden saidwork engaging head member is .not commensurate with the presetY position of said calibrated torque load control means, and Vmeans interposed between said calibrated torque load control means and said retainer trip means to position the latter in the path of said translatable means responsive to the presetting `of said calibrated torque load control means.

8. In a torque wrench, the combination with a yhandle member, of a torque responsiveY Work engaginghead member operatively connected in torque transmittingrelation With said' handle member and adapted to yield .in response to a torque loadthereon, translatable means connected Withsaid work engaging head member' to move vcommensurate with Vthe yield imparted thereto by the torque'load thereon, releasable indicator means, retainer trip means cooperable with said releasable indicator means .and disposable in the path of said ,translatable means, calibrated torque load control means operatively connectedr With said releasable indicator retainer trip means to presetthe position of the latter relative to said translatable means so'that the latter .will operate said releasable indicator means when said work engaging head member is subjected to a-torquev loadfor which said calibrated means has been preset, iiat spring means for normally urgingsaid retainer trip means to normally engage said indicatcrimeans in its extreme position of .displacement to indicate that the torque load on said work engaging'head member is not commensuratevvith lthe preset position of said calibrated torque load control means, means for normally urging said releasableV indicator and retainer trip means toward said translatable means, and means interposed between saidcalibrated torqueload controlmeans and said retainer-trip means to position the latter inthe path of said translatable means in a ,direction opposite to the displacement urge of said last named means responsive to the presetting of said `calibrated torque load ccntrol means.

Y9. ln a torque Wrench, the combination with a handle member, of a torque responsive Work engaging head member operatively connected in calibratedtorque load .control means operatively connected with said releasableindicator retainer trip. meansto `preset the v.position .ofthe latter relativetopsad translatable means sothat the latter will operate said releasable indicator means when said work engaging head member is subjected to a torque load for which said calibrated means has been preset, flat spring means for normally urging said retainer trip means to normally engage said indicator means in its eX- treme position of displacement to indicate that the torque load on said work engaging head member is not commensurate With the preset position of said calibrated torque load control means, spring means for normally urging said releasable indicator and retainer trip means toward said translatable means, and cam means interposed between said calibrated torque load control means and said retainer trip means to position the latter in the path of said translatable means in a direction opposite to the displacement urge of said last named means responsive to the presetting of said calibrated torque load control means.

10. In a torque wrench, the combination with a handle member, of a torque responsive work engaging head member operatively connected in torque transmitting relation with said handle member and adapted to yield in response to a torque load thereon, translatable means connected with said work engaging head member to move commensurate with the yield imparted thereto by the torque load thereon, a plate movably mounted to said handle member, releasible indicator means on saidy plate and disposable therewith in the path of said translatable means, said releasable indicator means having two extreme positions of adjustment for initial positioning to indicate that the torque load is below a preset value and for projected positioning when the torque load reaches a preset value, spring means for urging said plate toward said translatable means, and calibrated torque load control means operatively connected with said releasable indicator means to preset the position of said movably mounted plate relative to said translatable means so that the latter will operate said releasable indicator means when said work engaging head member is subjected to a torque load for which said calibrated means has been preset.

11. In a torque wrench, the combination with a handle member, of a torque responsive work engaging head member operatively connected in torque transmitting relation with said handle member and adapted to yield in response to a torque load thereon, translatable means connected with said Work engaging head member to move commensurate with the yield imparted thereto by the torque load thereon, a plate pivotally mounted to said handle member, releasable indicator means on said plate and disposable therewith in the path of said translatable means, said releasable indicator means having two extreme positions of adjustment for initial positioning to indicate that the torque load is below a preset value and for projected positioning when the 'torque load reaches a preset value, spring means for urging said plate toward said translatable means, and calibrated torque load control means operatively connected with said releasable indicator means to preset the position of said pivotally mounted plate relative to said translatable means so that the latter will operate said releasable indicator means when said work engaging head member is subjected to a torque load for which said calibrated means has been preset.

12. In a torque wrench, the combination with a handle member, of a torque responsive work engaging head member operatively connected in torque transmitting relation With said handle member and adapted to yield in response to a torque load thereon,` translatable means connected with said work engaging head member to move commensurate with the yield imparted thereto by the torque load thereon, a plate pivotally mounted to said handle member, spring means for urging said plate toward said translatable means, cam means for displacing said plate against the urge of said lspring means to accurately space said plate from said translatable means, releasable indicator means on said plate and disposable therewith in the path of said translatable means, said releasable indicator means having two extreme positions of adjustment for initial positioning to indicate that the torque load is below a preset value and for projected positioning when the torque load reaches a preset value, and calibrated torque load control means operatively connected with said releasable indicator means to preset the position of said pivotally mounted plate relative to said translatable means so that the latter will operate said releasable indicator means when said work engaging head member is subjected to a torque load for which said calibrated means has been preset.

13. In a torque wrench, the combination with a handle member, of a torque responsive work engaging head member operatively connected in torque transmitting relation with said handle member and adapted -to yield in response to a torque load thereon, translatable means connected with said work engaging head member to move commensurate with the yield imparted thereto by the torque load thereon, a plate pivotally mounted to said handle member, releasable Yindicator means on said plate and disposable therewith in the path of said translatable means, said releasable indicator means being mounted for projection proximate to said handle member to impinge in its released position against the turning force applying hand grasping said handle member, spring means for urging said plate toward said translatable means, and calibrated torque load control means operatively connected with said releasable indicator means to preset the position of said pivotally mounted plate relative to said translatable means so that the latter will operate said releasable indicator means when said work engaging head member is subjected to a torque load for which said calibrated means has been preset.

14. In a torque wrench, the combination with a handle member, of a torque responsive work engaging head member operatively connected in torque transmitting relation with said handle member and adapted to yield in response to a torque load thereon, translatable means conn ected with said work engaging head member tomove commensurate with the yield imparted thereto by the torque load thereon, a plate movably mounted to said handle member, releasable indicator means on said plate and disposable therewith in the path of said translatable means, said releasable indicator means being mounted for projection proximate to saidfhandle member to impinge in its released position against the turning force applying hand grasping said handle member, spring means for urging said plate toward said translatable means, and calibrated torque load control means operatively connected with said releasable indicator means to preset the position or" said movably mounted plate rela-` tive to said translatable means lso that the latter will operate said releasable indicator means when said Work engaging head member is subjected to a torque load for which said calibrated means been preset.

15. In a torque Wrench, the combination With a handle member, of a torque responsive Work engaging head member operatively connected in torque transmitting relation with said handle member and adapted to yield in response to a torque load thereon, translatable means connected with said work engaging head member to move commensurate with the yield imparted thereto by the torque load thereon, a plate movably mounted to said handle member, releasable indicator means on said plate and disposable therewith in the path of said translatable means, said releasable indicator means being mounted for projection proximate to said handle member to impinge in its released position againstthe turning force applying hand grasping said handle member, spring means for urging said plate toward said translatable means, calibrated torque load control means operatively connected With said releasable indicator means to preset the position of said movably mounted plate relative to said translatable means so that the latter will operate said releasable indicator means when said Work engaging head member is subjected to a torque load for which said calibrated means has been preset, and means on said calibrated torque load control means to retain its adjusted position against accidental displacement.

16. In a torque Wrench, the combination with a handle member, of a torque responsive Work engaging head member operatively connected in torque transmitting relation with said handle member and adapted to yield in response to a torque load thereon, translatable means connected with said Work engaging head member to move commensurate With the yield imparted thereto by the torque load thereon, a plate movably mounted to said handle member, releasable indicator means on said plate and disposable therewith in the path of said translatable means, said releasable indicator means being mounted for projection proximate to said handle member to impinge in its released position against the turning force applying hand grasping said handle member, spring means for urging said plate to- Ward said translatable means, and calibrated torque load controlmeans `operatively connectedv with said releasable indicator means lto preset the position of said movably mounted plate relative to said translatable means softhat'the latter will operate said releasable indicator means when said Work engaging head member is subjectedto a torque load for which said calibrated means has been preset, there being indentations on'said calibrated torque load control means to correspend with the calibrations thereon, and spring impelled detent means on said handle member to cooperate with said indentations to retain said calibrated torque load control means in its-adjusted position against accidental displacement.

17. In a torque Wrench, the combination with an elongated handle member, of a manual hand grasping portion on said handle member, a torque responsive work engaging member mounted to said handle member in torque transmitting relation therewith, calibrated torque load-presetting means on said handle member'for presetting a predetermined torque load value, and a releasable spring' actuated indicator mounted in said handle member to project exteriorly'thereof in the path of said hand graspingportion for retention and releasable control by said calibrated torque load presetting means, said spring actuated indicator serving as a Visual and audible and physical indication When the torque lloadonsaid Work engaging head member is commensurate with the preset position of said calibrated torque load presetting means.

References Cited in-the file of this patent UNITED STATES PATENTS Number Name. Date 1,512,192 Benko\ .Oct. 2l, 1924 2,242,613 Mandl May 20, 1941v 2,250,941 Zimmerman July 29, 1941 2,289,238 Brunelle July'7, 1942 2,300,652 Cooneyy Nov. 3, 1942 2,320,023 Zimmerman May 25, 1943 2,343,380 Larson Mar. 7, 1944 2,367,224 Larson et al Jan- 16, 1945 2,385,591 Sturtevant Sept. 25, 1945 2,442,359 I-Iattan June l, 1948 2,553,311 Greer May 15, 1951 FOREIGN PATENTS Number Country Date 621,277 France Jan. 31, 1927 

